1. Field of the Invention
The present invention relates to a pen-type optical mouse device and a method of controlling the same, and more particularly, to a pen-type optical mouse device and a method of controlling the same wherein a light guide causes light emitted from an illuminator to be incident on a surface at a predetermined angle, and a path of the light reflected from the surface is changed so that an image of the surface is imaged upon an image sensor, thereby allowing to write letters or draw a figure through a natural writing action.
2. Description of the Prior Art
A conventional mouse is a computer peripheral device which points a position by using a cursor displayed on a display device of a computer system and comprises a ball for allowing the change of a position and function buttons.
However, in such a conventional ball-type mouse, since the ball is not smoothly rotated on a slick surface, there is a limitation on a usage place and thus a mouse pad is required in order to ensure the smooth rotation of the ball. In addition, even if the ball of the mouse is rotated on the mouse pad, coordinate axes changed in accordance with the rotation of the ball do not exactly correspond thereto. Thus, there is a problem in that the cursor cannot be smoothly moved on the screen of the display device.
Further, in a case where a letter is inputted or a precision work is carried out using the ball-type mouse, a user has to operate a click button provided at the leading end of the mouse while holding and moving the mouse. However, in such a case, there are problems in that it is troublesome to perform such an operation of moving the mouse and thus the rapidity and accuracy of measurement of the coordinates are degraded. Particularly, there is a disadvantage in that since the shape of the mouse is different from those of general writing instruments, natural writing and drawing cannot be performed with the mouse. In addition, since the ball-type mouse essentially utilizes rotation of the ball, dust or the like may be collected between the ball and a device for sensing the rotation of the ball. Thus, there are disadvantages in that the durability of the mouse may be deteriorated and the interior of the mouse should be periodically cleaned.
Moreover, as for optical mouse devices for a computer which employ a method of detecting coordinates by using light, an optical mouse with an optical sensor and a pad combined, and an optical mouse employing a CMOS sensor have been used. The optical mouse with the optical sensor and the pad is constructed such that a coordinate detecting means including a light emitting element and a light receiving element, and a cross line pattern is inscribed on a mouse pad. In such a case, there is a problem in that since the optical mouse inevitably requires an exclusive pad, use of the mouse is limited.
Meanwhile, in case of the recently developed optical mouse employing the CMOS sensor, there are advantages in that an additional pad is not required contrary to a conventional optical mouse device, and its durability is improved since any moving parts are not employed therein. The principle of such an optical mouse is specifically disclosed in U.S. Pat. No. 6,233,368 B1 entitled “CMOS digital optical navigation chip” issued on May 15, 2001. In this patent, a work surface or sheet surface disposed directly below the optical mouse is illuminated with an illuminator (illuminating light source and its system) contained in the optical mouse; an imaging system contained therein images an arbitrary pattern or feature on the work or sheet surface on the plane of the CMOS sensor; and a processing unit detects a direction and the degree of movement of the mouse from variations in image information with time. In addition to such an optical mouse, U.S. Pat. No. 4,794,384 entitled “optical translator device” issued on Dec. 27, 1988 discloses the constitution in which when a work surface is illuminated with partially coherent light from a light source, a detector array detects changes in a speckle pattern reflected by the work surface so that movement of the mouse can be detected.
Such constitution has an advantage in that there is no limitation on usage environments thereof. However, since the shape of the mouse is different from those of general writing instruments, the movement of the mouse is performed in a state where the entire mouse is held in a user's hand and so it is difficult to achieve accurate coordinate movement. As a result, there is a problem in that it is not easy to perform a graphic operation or to write the user's signature using the mouse.
A pen-type mouse for implementing accurate cursor control when performing a delicate graphic operation or writing the user's signature has been developed. An example of such a pen-type mouse is disclosed in U.S. Pat. No. 6,151,015 (hereinafter, referred to as “'015 patent”) entitled “pen like computer pointing device” issued on Nov. 21, 2000. As shown in FIG. 1, the pointing device includes a cylindrical body 102, an illumination source 104, a lens 110, an optical motion sensor 108, a switch 106, communications links 116, 118, and buttons 112, 114. The illumination source 104 emits light, and the lens 110 allows reflected light, which is generated when the light emitted from the illumination source 104 is reflected off a work surface, to be imaged. Then, when an image of the work surface imaged through the lens 110 is captured with the optical motion sensor 108, a direction and amount of movement of the pointing device are obtained from variations in the image due to motion of the pointing device, and they are then transmitted to a computer through the communications links 116, 118.
However, the optical pointing device of the '015 patent has the following three disadvantages in performing a delicate graphic operation or smoothly writing one's signature.
First, there is a disadvantage in that it is difficult to hold the pointing device in one's hand due to large diameter thereof. Referring to FIG. 1, the optical motion sensor 108 for capturing the image of the work surface is disposed in a direction perpendicular to a central axis of the pointing device. Here, since the optical motion sensor 108, which is a kind of IC chip, has a standard size of a semiconductor chip, the dimension thereof in the (horizontal) direction perpendicular to the central axis of the pointing device is relatively longer than that in a (vertical) direction parallel to the central axis. Therefore, since the installation of the optical motion sensor 108 in the manner shown in FIG. 1 results in enlargement of the diameter of the pointing device, it is difficult to use the pointing device while holding it in one's hand.
The second disadvantage is that the motion of the pointing device cannot be accurately detected on a particular work surface. Referring to FIG. 1 again, since the optical pointing device of the '015 patent does not have a means for transferring the light emitted from the illumination source 104 to the work surface at a small angle, an angle Θ of the light from the illumination source 104 incident on the work surface may be increased, as shown in FIG. 2. Accordingly, if the work surface illuminated with the illumination source 104 does not have any patterns thereon or has the same color throughout the entire surface, there is a problem in that the motion of the mouse cannot be detected. FIG. 2 is a magnified view showing a work surface 21, such as that of copying paper, having a uniform color and no patterns. When viewing the surface with the naked eye under normal illumination, the irregularities of such a surface cannot be recognized. However, a general work surface actually has fine irregularities such as those of the work surface 21 shown in FIG. 2. In FIG. 2, if the angle Θ of the light that is irradiated from the illumination source 104 onto the work surface is over 40 degrees, the light is irradiated onto both left and right side slant surfaces 24, 23 of a convex portion. Thus, the left and right side slant surfaces 24, 23 of the convex portion cannot be discriminated therebetween in the image of the work surface imaged through the lens.
The third disadvantage is that when the pointing device is spaced apart from the work surface, the position of the cursor cannot be chased. Referring to FIG. 3, upon input of letters or figures, a writing operation with a pen is generally comprised of a combination of a pen-down action by which the pen comes into contact with a work surface and is then moved thereon, and a pen-up action by which the pen is spaced apart from the work surface and is then moved. For example, as shown in FIG. 3, when writing an alphabetic capital letter “X,” the writing action is comprised of a step of writing “/” through the pen-down action (step S1), a step of moving the pen through the pen-up action (step S2), and a step of writing “\” through the pen-down action (step S3). In general, in the pen-up action, the distance to be spaced apart from the surface is about 3 mm or less.
On the contrary, when it is intended to write the letter “X” by using the optical pointing device of the '015 patent, the pointing device comes into contact with the surface, a set button thereof is clicked, and then “/” is continuously written without a break (step S1). Subsequently, the set button is released, and the pointing device is moved to a proper position with being kept in contact with the surface (step S2). Then, the set button is clicked again, and “\” is written with the pointing device being kept in contact with the surface (step S3). Here, even when the pointing device is merely moved without inputting a letter (step S2), the pointing device should be in contact with the surface in order to chase coordinates thereof. If the pointing device is spaced apart from the surface, the distance between the surface 21 and the lens 110 is increased, so that the lens 110, which is designed to be properly operated under the condition that the pointing device is in contact with the surface 21, cannot cause the light to be accurately imaged on the optical motion sensor 108. Correct measurement of the coordinates cannot therefore be made in the state of the pen-up action, so that it is difficult to input letters or figures through a smooth or natural writing action.
The aforementioned writing action may be smoothly or naturally made only when the state where the mouse device is in contact with the surface and the state where the mouse device is not in contact with the surface are successively connected with each other. With such a conventional mouse device, since a letter or figure should be written or drawn only in a state where the mouse device is always in contact with the surface, it is difficult to smoothly perform the writing action and to correctly input a desired letter. Further, since almost all works are processed through the Internet at the present time, a case where a user should write his/her comment or signature on a document displayed on a monitor often takes place. However, it is very difficult to input a unique style of handwriting such as a signature with the conventional mouse devices. Accordingly, it is nearly impossible that the user realizes his/her signature on the monitor.
Consequently, in order to achieve the smooth input of the letter or figure, there is a need for a means capable of correctly measuring values of positions of the mouse device so that the coordinates thereof can be continuously chased irrespective of the state where the mouse device is in contact with the surface or not.
Meanwhile, even if the problems in the conventional pen-type optical mouse device required for a delicate graphic operation or a smooth writing operation may be solved, two other critical problems is expected. The pen-type optical mouse device is actually used in a slightly slanted state with respect to the work surface rather than in an upright state. Thus, the central axis (or longitudinal axis) of the pen-type optical mouse device is inclined at a certain inclination angle with respect to the direction (hereinafter, referred to as “z-axis”) normal to the work surface. As a result, the “y-axis” of the pen-type optical mouse device is influenced by the inclination angle, whereas the “x-axis” thereof is not influenced by the inclination angle. That is, a magnification in each of the “x-” and “y-” axis directions of the pen-type optical mouse device becomes different from each other. For example, if the user draws a circle with the pen-type optical mouse device, information on the motion of the mouse device is recognized as an ellipse having different ratios of width and height rather than the circle. Here, the aforementioned “x-,” “y-,” and “z-” axes are defined as follows. The “z-axis” is defined as the direction normal to the work surface or sheet surface, and the work or sheet surface, i.e. a plane normal to the “z-axis,” is defined as the “x-y plane.” At this time, the “y-axis” is defined as a straight line or direction that is included in a plane formed by both the normal (“z-axis”) and the central axis of the pen-type optical mouse device and is also placed in the “x-y plane.” The “x-axis” is defined as another direction that is perpendicular to the “y-axis” and simultaneously placed in the “x-y plane.”
In addition, the optical motion sensor 108 for capturing the image of the work surface utilizes its horizontal and vertical directions as reference directions for the motion of the mouse device. Since the pen-type optical mouse device generally takes the shape of a cylinder, the optical motion sensor disposed within the mouse device may be rotated from a reference angle in accordance with a posture in which the user grasps the mouse device. Accordingly, if the user grasps the mouse device in an unsuitable posture, a direction in which the mouse device is horizontally moved is not parallel to the horizontal direction of the optical motion sensor 108 contained in the mouse device. Thus, there is a problem in that the moving direction of the mouse device sensed by the optical motion sensor 108 is rotated at a certain angle from the actual moving direction thereof, thereby producing a distortion of the moving direction thereof.